Lesson T7.2.3

T7.2.3 The light year Quiz: KS3 Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T7.2.3, The light year: 20 multiple choice questions for the KS3 Physics (National Curriculum), Unit 7: Space physics, written with Revision Ninja.

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The 20 questions

  1. What is a light year?

    • The time it takes Earth to orbit the Sun
    • The distance from Earth to the Moon
    • The time light takes to travel one kilometre
    • The distance light travels in one year

  2. Roughly how far does light travel in one year?

    • About 9.5 trillion kilometres
    • About 150 million kilometres
    • About 300 kilometres
    • About 9.5 thousand kilometres

  3. What is the approximate speed of light in a vacuum?

    • 300 kilometres per second
    • 300,000 kilometres per second
    • 3,000 kilometres per hour
    • 30 kilometres per second

  4. Why are light years used to measure distances between stars?

    • Light years measure the mass of stars and the planets around them
    • Stars are only measured in metres, which is too small for their size
    • Light years measure how long stars last before they burn out fully
    • Those distances are too large to write easily in kilometres

  5. What is the approximate distance from the Sun to Earth in light minutes?

    • About 8 light seconds only
    • About 8 light minutes
    • About 8 light years
    • About 8 light hours

  6. Why is a light year a useful unit for astronomers?

    • It shows distance through how long light takes to reach us
    • It shows the mass of the object in a way that is easy to compare
    • It shows the temperature of the object at the surface of the star
    • It shows the speed of the object's orbit around its central star

  7. Which is further away from Earth?

    • A planet in our solar system
    • A star 4 light years away
    • The Sun
    • The Moon

  8. A star is 10 light years away. How long does its light take to reach Earth?

    • 10 minutes
    • 10 hours
    • 10 years
    • 10 seconds

  9. Which of these is a unit of time rather than distance?

    • Metre
    • Kilometre
    • Year
    • Light year

  10. What does the phrase 'light year' describe in the sentence 'The nearest star is four light years away'?

    • A time for the star to form
    • A distance
    • A colour of starlight
    • A brightness

  11. Which best explains why the light year is not a time unit?

    • It is the distance covered by light in a year
    • It measures the age of a star, from its birth to its death
    • It is always exactly one day long, so it is a measure of time
    • It measures how long light lasts before it fades away in space

  12. Light from a star 50 light years away left the star about how long ago?

    • About 50 years ago
    • About 50 minutes ago
    • About 50 days ago
    • About 50 seconds ago

  13. Why does looking at a distant star show the star as it was in the past?

    • The star changes colour as it moves
    • Its light took a long time to reach us
    • Its light is slowed down by air
    • Its light is always produced in the past

  14. Which of these distances is the largest?

    • 10 light years
    • 10 light minutes
    • 10 light seconds
    • 10 light hours

  15. Which unit would be most sensible for measuring the distance from Earth to the Moon?

    • Kilometres
    • Light hours
    • Light years
    • Light years multiplied by ten

  16. What is the approximate distance of the nearest star to the Sun, Proxima Centauri, in light years?

    • About 4.2 light years
    • About 0.42 light years
    • About 420 light years
    • About 42 light years

  17. Which of these is the best description of a light year?

    • A unit of distance used for measuring huge distances in space
    • A unit of mass used for measuring the planets in our solar system
    • A unit that measures the power output of a star in space
    • A unit used to measure the length of a day on the planet Earth

  18. Why would a light year be a poor unit for measuring the length of a pencil?

    • It would be too small to measure a pencil accurately with any ruler
    • It is far too large, so the numbers would be extremely small
    • Light cannot travel far enough to measure something as short as a pencil
    • A pencil cannot be measured in any distance unit at all, so it cannot be done

  19. What is the distance from Earth to the Sun in kilometres, roughly?

    • About 15 kilometres
    • About 150 million kilometres
    • About 150 thousand kilometres
    • About 150 billion kilometres

  20. Which statement about a light year is correct?

    • It changes with the observer's speed, so it is not a fixed distance
    • It is a fixed distance, the same for any observer
    • It changes with the season on Earth, as the year is different each time
    • It depends on the size of the star that is being measured in space

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